mac os 调用ffmpeg静态库，编译失败

[lovexiaokai]

#include <iostream>
using namespace std;

extern "C" {
#include "libavcodec/avcodec.h"
}
int main(int argc, const char * argv[]) {
// insert code here...
avcodec_register_all();
cout << "Hello, World!\n";
return 0;
}
源码如上，编译报错如下
Undefined symbols for architecture x86_64:
"_avcodec_register_all", referenced from:
_main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
配置如下，请问如何解决， 试了网上的办法， 也不行。求指教